2 speed tranny w/ 2nd gear as "turbo' ?

[BrianG]

66/26...hmm. IMO, I think that's a little high. It's a start anyway, especially if you don't have the other pinions to test. I do know that a couple of teeth can make quite a difference, so I wouldn't trash the idea if 26t doesn't work out for you. If I was a betting man, I'd say your sweet spot will be 20t or 22t for what you're aiming for. I really think any higher and the motor will be overgeared.

As far as calculations, I used my web version, which is similar to yours. I rounded when posting the numbers so that's probably the difference.